Add a android-base shim for floss

The code generated by the sysprop tool depends on some
APIs of android-base to read properties to make it
work on floss we add the needed API and wire them to
the GD OS APIs

Bug: 337064224
Test: None
Flag: EXEMPT, floss
Change-Id: Ifa8491b475cd2461904eb42a40a96713c43bf459